Molybdenum alloy



July 9, 1940. J. KURTZ 2,207,380

MOLYBDENUM ALLOY Filed April 15, 1940 INVENTOR. and: K fi 4MMA ml Patented July 9, 1940 UNITED STATES PATENT OFFICE MOLYBDENUM ALLOY poration of Delaware Application April 13, 1940, Serial No. 329,441

2 Claims.

This invention relates to new and useful improvements in molybdenum alloys and more particularly to an alloy that when formed into a wire has certain characteristics which make it exceptionally suited for use in thermionic valves and the like.

According to the present invention the alloy consists of 18 10 per cent. of molybdenum, 2-5 percent. of manganese, .25-.5 per cent. of silver,

* and the balance nickel. Good results have been obtained with an alloy containing 21 per cent. molybdenum, 2 per cent. manganese, .5 per cent. silver and 76.5 per cent. nickel.

The nature of the invention will be explained 35 with the aid of the drawing which shows curves comparing the elongation characteristics of my improved wire B with a wire A of substantially the same tensile strength but formed of a different molybdenum alloy.

The curve A represents the elongation characteristics of wire formed of a nickel molybdenum alloy containing 5 per cent. of iron, or more, and containing no silver. B is the corresponding curve of a wire made of my improved alloy. The

abscissa represents elongation in percentage and the ordinate load in grams.

Up to a load of about 600 grams neither wire stretches. Between 600 and 800 grams load, the wire A stretches substantially uniformly as the 80 load is increased, while the curve of my improved wire forms a decided knee.

When the load is increased from about 640 grams to about 700 grams. wire A stretches by about 5 per cent. and wire B by less than 2 per 35 cent. Then up to 760 grams the curve A is very steep, the wire stretching only about 1 per cent. Curve B, on the other hand, has substantially the same slope between 700 and 760 as it had between 640 and 700. Above 760 the two wires behave in 40 the same manner.

It will be understood. of course, that the quantitative values are given merely for the sake of illustration, and will vary with the diameter, composition and processing of the wire. The drawing is presented only to show that at the critical point during the winding operation my improved wire becomes work-hardened which is illustrated by the knee in the critical portion of curve A. In the example this critical point is between 700 and 760 grams much beyond which the wire will not be loaded during the winding operation. The wire will thus acquire just the right amount of springiness necessary to insure that the finished grid will retain its shape whe it is removed from the mandrel.

My present theory is that the improved charw acteristics owe their origin to precipitation hardening produced by the silver, and to the absence of iron from the alloy. Not only do not I add iron but as far as possible I eliminate it even as an impurity by using electrolytically deposited nickel and manganese, and chemically pure silver.

My new alloy may be produced according to any well known method. My preferred method is to place the nickelin a suitable crucible and melt it as quickly as possible in an induction furnace. The molybdenum, manganese and silver are then added in the order named as each one goes into solution. Solution may be hastened by the use of a stirring rod of nickel or molybdenum. After the mass has reached the molten condition and 25 all the ingredients have bene uniformly dissolved and stirred into the molten metal, the resultant alloy may be poured into a suitable mold.

The alloy may also be produced by mixing the constituents as powders and then milling and pressing them into ingots which are sintered at a temperature slightly below the melting point until a uniform homogeneous sintered bar is produced.

What is claim is:

1. An alloy having substantially the following composition: 18-40 per cent. molybdenum, 2-5 per cent. manganese, 25-5 per cent. silver, and the balance nickel.

2. An alloy having substantially the following 40 composition: 18-40 per cent. molybdenum, 2-5 per cent. electrolytically deposited manganese, .25-.5 per cent. chemically pure silver, and the balance electrolytically deposited nickel.

JACOB KURTZ. 

